The present invention is directed to a device for the electrodeposition of aluminum from an aprotic, oxygen-free and water-free aluminum-organic electrolyte. The device comprises an annular electroplating tank which comprises an annular vat filled with the electrolyte and anode plates and covered by a hood to provide a protective atmosphere that is isolated from the outside. To support and move workpiece holders through the annular vat, the tank includes a rotatable support rack having brackets extending radially from a vertical axle and having receptacles for receiving the workpiece holder to suspend the workpiece holder in the vat for rotation on the curve. The tank also includes a charging lock and a discharging lock so that the brackets can be loaded and unloaded without contaminating the atmosphere and the electrolyte of the tank.
A device for electrodepositing of aluminum from an aprotic, oxygen-free, water-free aluminum-organic electrolyte, which device has a lock system with a liquid lock for introduction and removal of the goods to be electroplated is disclosed in U.S. Pat. No. 4,265,726 which was based on German OS No. 2,901,586. In the device of this patent, the goods, which are to be electroplated, are accommodated on workpiece supports or workpiece holders which can be introduced with the assistance of an endless conveyor belt from an antechamber floodable with an inert gas through a liquid lock and into an electroplating bath or vat. After the electroplating has been accomplished, the holder is again transferred in the reverse direction with the assistance of the same conveyor belts. A disadvantage of this known device is that a rather considerable amount of the electrolyte is entrained from the electrolyte vat or bath into the liquid lock. Due to this continuing contamination of the liquid forming the liquid lock with the electrolyte, an unavoidable reaction with traces of air or moisture in the antechamber flooded with the inert gas will occur. These reaction products cannot be prevented from being deposited at unfavorable locations on the workpiece, which is to be aluminized and which was previously cleaned, as the workpiece is transported into the electroplating space through the liquid lock which acts both as a charging and discharging lock. Therefore, these parts can no longer be coated with technically usable aluminum coatings. In addition, since only a single workpiece holder can be introduced into the device at a time, the device is not suited for mass production of plated articles.
In an earlier patent application, U.S. Ser. No. 318,812, filed Nov. 6, 1981 and based on German patent application No. 3,044,975, a charging lock is provided for introducing of the workpiece holders or carriers and also a discharging lock is provided for allowing the removal of the workpiece holders containing the plated workpiece. In order to increase the amount of throughput, it is further proposed that the known electroplating tank be employed with an annular closed or isolated electroplating vat in which a multitude of workpiece holders can be simultaneously accommodated. For this reason, the electroplating tank contains a support device for the workpiece holders which both contacts and holds the workpiece holders. This device is rotatable around a vertical axis of rotation and has brackets for receiving each of the workpiece holders so that they are moved in a circular arc or path in a substantially horizontal plane. As a result of the annular design of the electrolyte bath or vat, the workpiece holders can be moved through the electrolyte in a circular path and by so doing can be coated with aluminum at a higher current density. This device has proven itself.